Typo in migration class name was causing a constant missing error
Boolean -> String quoting has changed on Rails master

CustomField.create(name: 'zomg', value: true).reload.value # => 't' on Rails 4.1, '1' on 4.2

rails/rails@42be84ba
Forgot to commit Gemfile.lock as well
Lock down fabrication gem version due to a regression

It appears that there is a regression within the fabrication gem somewhere
between 2.9.8 and 2.11.3. Specifically...

   let(:post) { Fabricate(:post) }
   let(:second_post) { Fabricate(:post, topic_id: post.topic_id) }

On 2.9.8, both `post` and `second_post` points to the same topic. However, on
2.11.3 second_post has a different topic. This is causing some failure with
RAILS_MASTER=1 (this example is taken from post_action_spec.rb).

Not sure why yet – an educated guess is that perhaps the order that attributes
are applied have changed. The factory defines a `topic` attribute where we are
trying to override `topic_id` instead. I suppose which one of the two wins would
depend on which of the two are set last?

Anyhow, this does the trick for now.